Amuro finished his reflection on that time, nearly a century ago. He
tightened the mantle of black with red clouds that he wore. He made
dead-sure his black ceramic mask with a red question mark emblazoned on
its surface was secured. Then he took one last, eyeless look upon the
three pedestals in the chamber with him. The Stone of Spirit, glowing
ruby; The Stone of Body, glowing emerald; The Stone of Nature, glowing
gold… Three of the Six Sage Stones were in his possession. It was
finally time to claim one more from where it had been hidden. It was in
the possession of the Hokage, Senju Hashiramako. She had hidden it. And
Amuro had used Uchiha Fuyu to find that hidden location. Fuyu was once
again too weakened to stop him from manipulating her. It was time to
retrieve that information and take the Stone of Yin-Yang to add to his
collection.
'Nagato, don't…!' the ghost of Uzumaki Natsu warned inside of Amuro's
head. The masked man simply said out loud, "It's too late to go back now.
I know what your idea of justice is. But you have your justice… And I
have mine." It was time to go to Uchiha Fuyu's hospital room. She would be
unable to stop him. Her memories would be his, and then so would the
Stone. He would just have to hope the Hokage wasn't in her office today,
or this could get messy.
A pinpoint of a pinpoint of a pinpoint, a hole in the universe itself,
appeared at the center of Amuro's being. He absorbed himself into the Void
of the Munashiigan — his birthright, his bloodline, his curse — and was
gone.

Shortly after Amuro was no longer present in his chamber, the malevolent
cloud of evil given form, known as the Beast of Blood, began to laugh to
itself. It was flowing through various Seal-regulated pipes within the
private chamber, all to contain its growing power that not even Amuro
could manage alone. What he didn't realize was that by spreading out the
Beast of Blood throughout Mountains' Graveyard, he was giving the
Yin-Beast the ability to observe all that went on in this fortress… He
also didn't realize the reason he was making use of this method of pipes
channeling raw evil to begin with was that he had already fallen under the
monster's influence himself.
No one was present to hear it, but the voice of the abomination made
infants wail, pets go into a frenzy, and Sensor-Nin hundreds of miles
around shudder without knowing why. The creature crooned a single
sickening, hate-filled word of reassurance to itself in the voice of all
the wickedness of humanity.
It spoke only one word.
"Soooooon…"